I know the Q wasn’t about the difference but here are some real life examples:
Roosting Serendib Scops Owl in deep shade. With 8s you could see the spots. With 10s, you couldn’t.
Lagden’s Bush-Shrike high in a canopy. We all borrowed a mate’s 10s for better views.
Pechora Pipit creeping through a dense patch of overgrown garden on Shetland. Mate with 10s couldn’t get on it, but ok with 8s. (he’d already seen it well by the way)
A warbler in brambles at the edge of a Dorset marsh the other day. Clearly a crest of some sort in 10s, just a warbler type in 8s. Was a Goldcrest actually.
I now use 10x all the time in Britain although I’d happily use 8s. I take both abroad though and often switch to 8x for a day in the forest. I think it’s absolutely ridiculous that there is no top of the range 9x35 or 36 on the market.